- Do not switch off the phone
Your phone's battery charge will last longer if you don't turn it off. The reason for this is that smartphones are actually pocket-sized computers with a phone built into them, and just like PCs, smartphones take a while to boot up, and this booting process involves lots of intensive computing processing. If you switch a phone on and off lots of times, it will use up the battery very quickly because you're asking it to boot up lots of times. Your battery will last a LOT longer if you just leave the phone on all the time, and charge it while it's still on.
- Shut down unnecessary applications
Some smartphones like S60 smartphones can run several applications at once (for example you can listen to music while surfing the web and receiving instant messages). However, the more applications you run at the same time, the faster the battery will be drained, so it's a good idea to shut down any applications you don't need.
- Turn down the screen brightness to the lowest acceptable level
One of the biggest battery drains on portable devices is the screen's lighting system, which is why mobile device screens usually dim themselves when they're not in use.
- Switch off the screen when not in use
When you're not using the smartphone it's a good idea to lock the screen, partly because it stops the screen being touched by mistake, but also because it switches the screen off too. The phone itself carries on running, but the screen being off will make the battery last a lot longer.
- Use headphones instead of speakers
If you listen to music on smartphone's built-in speakers you will use the battery up more quickly than if you listen through headphones. Headphones are inside your ear so they use much less power to deliver the same intensity of sound.
- Avoid using the camera flash unnecessarily
There are many situations when your smartphone camera will automatically use the flash even though you could get a reasonable photo without it. In those circumstances you may want to switch the flash off because it's using up the battery unnecessarily.
- Use 2G instead of 3G
The advantage of 3G is a very high speed internet access. In fact, the latest 3.5G HSDPA technology allows you to use speeds up to many megabits, comparable to PC broadband connections. The disadvantage of 3G networks is that they use up a phone's battery more quickly during calls. Usually, a smartphone will use GSM/CDMA for 2G and UMTS/WCDMA for 3G. By default most smartphones use 3G networks, but can automatically switch to 2G when there is no 3G network available in the location. If you don't need high speed internet access, try switching your phone into 2G-only mode in order to save battery life during phone calls.
- Try to get a good signal
The better the signal on your phone, the easier it is for the phone to connect to a base station. The easier it is to connect to a base station, the less power a phone uses during calls. You can get a better signal by being out in the open, or if you're indoors try to be near windows.
- Use Offline Mode or Flight Mode
If you're using your smartphone just to do offline stuffs like listening to music or watching a video, and you don't need to take any calls on it, you might want to switch it into Offline mode or Flight mode. Offline mode means that the phone switches off anything which involves radio transmissions, such as phone calls, text messages, internet connections, Bluetooth or Wi-Fi. Offline mode saves a certain amount of battery life as the phone no longer has to use its radio transmitters.